By Karen Pihl-Carey

ImmunoGen Inc. entered into an agreement with British Biotech plc to develop and market a tumor-activated prodrug in preclinical trials to treat small-cell lung cancer (SCLC).

The companies plan to bring the drug, huN901-DM1, into Phase I testing in the fourth quarter of this year. At that time, British Biotech, of Oxford, England, will take over development costs as part of its agreement with ImmunoGen.

"We had earlier stated that it was our intention to go up to and include the filing of the IND [investigational new drug application] on our own, but that we would not go into the clinic without a partner," said Mitchel Sayare, chairman and CEO of Cambridge, Mass.-based ImmunoGen. "We're very pleased that strategically we're fulfilling our objectives."

The agreement gives British Biotech exclusive development and marketing rights in the European Union and Japan, in return for an up-front fee of $1.5 million and responsibility for conducting the clinical trials necessary to achieve regulatory approval in the U.S. ImmunoGen retains the rights to market huN901-DM1 in the U.S. and the rest of the world, as well as the right to manufacture the product worldwide.

ImmunoGen also will cover the remaining preclinical development and will be reimbursed for manufacturing the product for clinical trials.

When and if the product receives marketing approval in the U.S., ImmunoGen will pay British Biotech a one-time, undisclosed milestone payment. ImmunoGen will receive undisclosed royalties on sales of the product in Europe and Japan.

ImmunoGen chose to partner the product with British Biotech for several reasons, including the fact that the company could retain its U.S. rights, Sayare said.

"British Biotech is probably the most experienced company in conducting human clinical studies in small-cell lung cancer," he told BioWorld Today. "And the way that the cost burden on development of this product is distributed, it makes a lot of sense to us. It does not drain our cash, and it offers us an enormous return for what we have put into this product."

Elliot Goldstein, CEO of British Biotech, said the collaboration broadens his company's approach to cancer treatments beyond the area of metalloenzyme inhibition.

A tumor-activated prodrug (TAP), HuN901-DM1 consists of a humanized monoclonal antibody (huN901) targeting SCLC cells, coupled with a highly potent cytotoxic agent (DM1), a maytansine derivative. In preclinical studies, the product eradicated SCLC tumors, while cisplatin and etoposide, current treatments for SCLC, produced only temporary interruption of tumor growth, ImmunoGen said.

ImmunoGen's most advanced TAP, huC242-DM1/SB-408075, has been licensed to SmithKline Beecham plc, of London, and is in Phase I/II trials for colorectal and pancreatic cancer. To date, ImmunoGen has received $9.5 million in milestone payments from the collaboration.

On Thursday, ImmunoGen entered into a deal with Genentech Inc., of South San Francisco, giving Genentech exclusive worldwide rights to commercialize anti-HER2 targeting products using ImmunoGen's maytansinoid TAP platform. In addition to an up-front payment of $2 million and potential royalties, the deal could mean up to $40 million in milestone payments for ImmunoGen. (See BioWorld Today, May 5, 2000, p. 1.)

ImmunoGen's stock (NASDAQ:IMGN) closed Friday at $11.56, up 56.25 cents.

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